于是 应该是It's adj for/of sb to do sth （俩介词相连是不可能的亲）。然后of的话，应该是说自身的性质，也就是你给外界带来的影响。比如it’s so nice of you to come.这句话是你特别好，所以用of。for的话就是外界对你带来的影响。it's hard for me to read this book.这句话是看书对你的影响（难）所以~亲你懂得~然后enough一般情况下肯定用for咯。It's enough for me to marry her~...
这个属于固定搭配 It's+adj+for/of+sb+to do sth例如It's kind/nice of you... 你真好It's important/difficultfor you to do... 对你来说做...很重要/很难需要看情况enough 用It's enough for you to do......
